Garp is the illegitimate son of nurse Jenny Fields and one of her patients, a pilot who died before Garp was born. Garp grew up insisting he knew his father, and wanting to have any possible connection to him.

Things then get worse. Although Helen and Garp have two wonderful sons, Helen begins having an affair. Jenny moves in with a houseful of distressed women. And then Garp, in his anger, makes a horrible mistake that affects his whole family.